Sexual dysfunctions are rarely caused by a single factor, although one may predominate. The question is not, ‘Is this problem physical or psychological?’ but ‘How much of each kind of factor operates in this case?’ Similar causative factors operate in men and women, but their manifestations are more obvious in men. It is easy to overlook women’s problems unless special inquiry is made. Biological factors occur often in the course of chronic physical and mental illnesses. Hypogonadism is a well-recognised cause, but is not common.

Sexual difficulties are rarely due to testosterone defi ciency in men or menopausal or menstrual irregularities in women, though the possibility is often entertained, perhaps because doctors are less comfortable evaluating psychological and relationship factors. It is often the case that no defi nite biological cause can be found in a particular patient, and other mechanisms are presumed to operate. Selective serotonin reuptake inhibitors (SSRIs) are well known to cause sexual dysfunction, especially paroxetine, fl uoxetine and sertraline. Tricyclic antidepressants can cause differential effects on domains of sexual functioning. Moclobemide and bupropion are said to have less sexual side effects. Antipsychotics such as thioridazine produce various sexual side effects, although the data are mixed. Even atypical antipsychotics such as olanzapine and clozapine cause sexual dysfunction.

In managing sexual dysfunction under these circumstances dose reduction, drug holidays and adjuvant therapies may help. During development, individuals acquire from their experiences of care givers and other personal models a concept of what people are like. Traumatic experiences with adults during childhood may contribute to later sexual and relationship preferences. However, there is no specifi c connection between particular experiences of early abuse and later problems, and it is remarkable how often people with awful early experiences emerge relatively intact. Nevertheless, the responses of an adult to a prospective sexual partner are framed by expectations of how ‘a person like that’ will behave. Cognitions (thoughts) and moods (emotions) shape each person’s experience of sexual arousal and behaviour. Attentional processes are important: in the common experience of spectatoring, people focus on their own performance, often expecting failure, rather than on the sensuality of lovemaking. Pain, ruminations and worries divert attention. Intense negative emotions tend to reduce sexual activity and performance, but the association is not close. In depression, sexual enjoyment is often diminished but occasionally increased; the preferred erotic behaviour may alter, often becoming more passive; and antidepressant drugs may adversely affect sexual response.

Misunderstanding, ignorance, unsuitable circumstances for having sex, guilt and bad feelings about sex and/or partner can contribute to anxiety and fear of failure, leading to sexual dysfunction.